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DLP4710EVM-LC: Internal Patterns Flickering

George Huang
Prodigy 10 points
Part Number: DLP4710EVM-LC

Tool/software:

Hello,

I'm encountering a flickering issue when projecting 1-bit vertical pattern 

here is  a screen shot showing my projection setting

Has anyone encountered a similar issue or know how to resolve it?

Thank you.

  • 0
    TI__Guru 54285 points

    Hello George,

    Today is a holiday here.  I have assigned this ticket to the expert who can help you with this.  They will get back to you on this.

    Fizix

  • 0 in reply to Fizix
    TI__Genius 11800 points

    Hello George,

    We will try and recreate this on our end. Could you advise if the projection is not following your programmed patterns?

    Oftentimes when we see frequencies with our eyes we may see it as "flickering" or often seen with camera shutter-speeds as optical illusions. Could you advise more about this "flickering" and where you are seeing it?

    The latest Firmware Release (v8.4.0) release notes show that the exposure time range for 1-bit RGB patterns is 600-7600. It is also mentioned, "[l]onger exposure times will operate with decreased timing accuracy and behavior is not guaranteed."

    Best,

    Aaron

  • 0 in reply to Fizix
    TI__Guru 54285 points

    Hello George,

    We were able to recreate what you are seeing.  I think the issue here is a misunderstanding of what is happening in the pattern timing.  I duplicated what you have above.

    Then I created a solution with just two patterns to see how the pre-exposure dark time, exposure time, and post-exposure dark time interact:

    As you can see, the pre-exposure, exposure, and post-exposure are applied to each image in the set.  Not just to the beginning and end of the set.

    This means each pattern will take 112,000us (112ms)  - a little shy of 1/8 sec.  That is about 9Hz which your eyes will definitely see.

    In your solution you will see the pattern flash R, G, B each for 33ms followed by 12ms of dark (pre+post).

    I hope this makes it clear.

    Fizix